Merge branch 'jk/unused-post-2.42-part2'

Unused parameters to functions are marked as such, and/or removed,
in order to bring us closer to -Wunused-parameter clean.

* jk/unused-post-2.42-part2:
  parse-options: mark unused parameters in noop callback
  interpret-trailers: mark unused "unset" parameters in option callbacks
  parse-options: add more BUG_ON() annotations
  merge: do not pass unused opt->value parameter
  parse-options: mark unused "opt" parameter in callbacks
  parse-options: prefer opt->value to globals in callbacks
  checkout-index: delay automatic setting of to_tempfile
  format-patch: use OPT_STRING_LIST for to/cc options
  merge: simplify parsing of "-n" option
  merge: make xopts a strvec

builtin/add.c

@@ -231,6 +231,8 @@ static char *chmod_arg;
 
 static int ignore_removal_cb(const struct option *opt, const char *arg, int unset)
 {
+	BUG_ON_OPT_ARG(arg);
+
 	/* if we are told to ignore, we are not adding removals */
 	*(int *)opt->value = !unset ? 0 : 1;
 	return 0;